The OECD has failed in its efforts to reform the international tax system despite several deals in recent years, the Tax Justice Network said Tuesday, calling for the United Nations to take over responsibility.

The Organisation for Economic Cooperation and Development, a club dominated by rich nations, has helped set global tax rules for decades and has been working to reform them given rampant abuse by multinational firms.

In 2021, in talks led by the OECD, agreement was reached on a minimum tax rate of 15 percent on multinationals and to develop rules on how to tax multinationals so countries do not lose out by profit shifting.

But implementation of the minimum rate and development of the tax rules have been slow.

"No significant reductions have been made in the amount of tax countries lose to global tax abuse since the start of the OECD's efforts to reform global tax 10 years ago," said the Tax Justice Network.

The Britain-based NGO said that several studies, including one by the IMF, conclude that the OECD's draft proposals will make little to no impact on the scale of tax losses.

The Tax Justice Network estimated that if countries follow the course they have for the past decade, they will lose $4.7 trillion over the next 10 years.

For comparison, the NGO says the 2007-2009 Great Recession was estimated to have led to a loss of $2 trillion in global economic growth.

The Tax Justice Network said many of the OECD's proposals are serious and in line with its own.

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"However, in all cases these policies have been rendered largely toothless under the pervasive influence of some OECD members who are also among the world's biggest tax havens," it said.

The NGO estimated that OECD nations are responsible for 77 percent of the $472 billion in tax losses countries suffer each year.

Higher income countries suffer most of the losses, but the figure is less than a tenth of their public health budgets, while for lower income nations it represents 56 percent.

That is one of the reasons why the Tax Justice Network believes the United Nations would be a better forum to reform global tax rules.

"The Tax Justice Network is urging countries to support moving leadership on global tax from the OECD to the UN, where global membership, public transparency and the UN's human rights legal frameworks and technical expertise can provide a more viable forum for securing effective tax solutions," it said.

Nations opened the door last year to negotiations on a UN tax convention and the secretary general is expected to present a report at the general assembly in September about options to move forward.

The Tax Justice Network's chief executive Alex Cobham said experience has shown that a handful of countries and lobbyists have been able to undermine tax reform via the OECD.

"We now have a real shot at bringing this process into the daylight of democracy at the UN, where all countries will finally get a real say, and where governments will finally have to answer to their people on tax policy," Cobham said.